Feasibility of an efficient recovery of rare earth-activated phosphors from waste fluorescent lamps through dense-medium centrifugation

T. Hirajima, K. Sasaki, A. Bissombolo, H. Hirai, M. Hamada, M. Tsunekawa

Research output: Contribution to journalArticlepeer-review

66 Citations (Scopus)

Abstract

Experiments were carried out with waste phosphors collected during the recycling of end-of-life fluorescent lamps to obtain a highly enriched phosphors product as starting material for the better extraction of rare earth elements. The aim of this work was therefore to separate low-density calcium halo-phosphate phosphors from high-density rare earth-activated phosphors through dense-medium centrifugation (with di-iodomethane as organic dense-medium). The feasibility of the process and the conditions for a good separation (higher Newton's efficiency) appear to be a function of the rotation speed of the centrifugal separator, the pulp concentration and the adsorption of a surfactant (sodium oleate, NaOl) during the pre-treatment stage. The effect of the centrifugation time was less pronounced. Through this study, a sink product assaying 48.61% of rare earth-activated phosphors could be recovered from waste phosphor materials pre-treated with 5 × 10-5 mol/dm3 of sodium oleate (NaOl) surfactant. The Newton's efficiency and recovery of the separation were 0.84 and 97.34%, respectively. The process feasibility was reinforced by the possibility to recover, through laboratory batch tests, more than 99.8% of the di-iodomethane (CH2I 2).

Original languageEnglish
Pages (from-to)197-204
Number of pages8
JournalSeparation and Purification Technology
Volume44
Issue number3
DOIs
Publication statusPublished - Aug 2005

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Filtration and Separation

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